Fabrication of CaO pellets via polyvinyl alcohol (PVA) method for efficient CO2 capture and solar energy storage.

• Porous CaO-based spherical pellets were prepared via indirect and direct polyvinyl alcohol (PVA) method. • Energy storage property as well as CO 2 capacity was evaluated under different operating conditions. • CaO pellets possessed excellent energy storage density of 2741 kJ/kg during ten energy storage cycles. • The cyclic CO 2 capture performance of CaO pellets was positively correlated with the tested carbonation temperatures. Calcium looping (CaL) exhibits great prospects for both thermochemical energy storage and CO 2 capture. The granulation of CaO into spherical pellets is a crucial step for its practical application. In this study, a PVA solution was utilized as a binder to prepare CaO spherical pellets. Two different methods including the direct method and indirect method assisted with PVA solution were employed to produce CaO pellets. The experimental results indicated that the carbonation conversion of the sorbents from the indirect method was significantly superior to those from the direct method. For energy storage, CaO pellets decomposed from calcium hydroxide using indirect method exhibited satisfying energy storage density, starting with 3200 kJ/kg at the 1st cycles and ending with a high level of ∼2400 kJ/kg over 10 cycles. In the CO 2 capture performance test, CaO spheres prepared with calcium citrate as a precursor showed promising CO 2 capture performance at around 700 °C. In addition, the effects of carbonation temperature on the energy storage and CO 2 capture performance were also studied. It was indicated that CaO pellets exhibited better cyclic energy storage performance at 750 and 800 °C, and that performed best when carbonated at 700 °C for cyclic CO 2 capture. Besides, the pellets also demonstrated good mechanical properties such as satisfactory long-term anti-attrition ability, further supporting the practical viability of CaO pellets for both thermochemical energy storage and CO 2 capture applications. [ABSTRACT FROM AUTHOR]